Convert 3DM to OFF (Free)
Also converts STL, OBJ, GLB, PLY, USDZ, 3MF from the same file.
Runs in your browser. No upload, no signup, nothing to install.
Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.
How to convert 3DM to OFF
- 1
Open your .3dm file
Drag it onto the viewer above, or click "Open a 3DM File". Files up to 200 MB open directly; the parse runs in a worker so the page stays responsive.
- 2
Pick Object File Format in the Export menu
Click Export in the toolbar, then OFF (.off).
- 3
Download
The .off is written in the browser and saved straight to your downloads folder. No queue, no email, no watermark.
What survives the conversion
A file conversion is a translation, and formats do not carry the same things. Here is exactly what moves from 3DM into OFF, and what does not.
| Geometry | Reduced | 3DM stores exact B-rep solids and OFF stores triangles, so the surfaces are tessellated. Curved faces become faceted at the display tolerance, which is fine for visualization, printing and clash checking, but not for further parametric CAD work. |
|---|---|---|
| Colors and materials | Reduced | 3DM can hold material colors and OFF holds per-vertex color, so materials are flattened to that. |
| Layers and structure | Dropped | OFF is a single flat body with no layers or named parts. Everything merges into one object. If you need the structure, export to GLB, OBJ, DXF instead. |
| Units and scale | Dropped | OFF stores no unit. Coordinates are written in meters, so set the import unit to meters if the destination asks. |
| Lines and points | Dropped | OFF has no line or point primitive, so line work and point clouds are skipped: only the triangle mesh is written. |
What the OFF writer emits: ASCII OFF (COFF when any vertex carries color), one merged vertex/face list, verbatim in scene units.
The source: Rhino 3D Model (.3dm)
Rhino meshes, NURBS surfaces and polysurfaces, SubD, curves, point clouds, layers with their colors, and the file unit system.
The target: Object File Format (.off)
The plain geometry-exchange format used by mesh-processing research tools.
Opens in: MeshLab, CGAL, libigl, geomview.
Your file never leaves your computer
Both the 3DM parser and the OFF writer are JavaScript and WebAssembly running in your own browser tab. There is no upload step, no server-side conversion queue, and no copy of your file anywhere but your machine. That matters for drawings under NDA, for client work, and for anything you would not email to a stranger.
Free to Use, No Signup
There are no accounts and no watermarks on this converter. If it saved you time, the one thing we ask is a mention: a post, a link from your blog or course page, or a reply to someone asking how to open a file.
Share it
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Hear about new formats
Occasional emails when the viewer learns a new format or gets a new tool.
Frequently asked questions
▶Is this 3DM to OFF converter free?
Yes. No signup, no watermark, no per-file limit and no paid tier. Innerscene.
▶Is my 3DM file uploaded anywhere?
No. The file is read with the browser file API and converted in the same tab. Nothing is sent to a server unless you explicitly click Share, which is a separate, opt-in feature.
▶Will my colors and materials survive the OFF export?
3DM can hold material colors and OFF holds per-vertex color, so materials are flattened to that.
▶Do layers and named parts carry into the OFF file?
OFF is a single flat body with no layers or named parts. Everything merges into one object. If you need the structure, export to GLB, OBJ, DXF instead.
▶Will the OFF open at the right size?
OFF stores no unit. Coordinates are written in meters, so set the import unit to meters if the destination asks.
▶How large a 3DM file can I convert?
Up to 200 MB, and the ceiling adapts to how much memory your device reports. The conversion runs on your own hardware, so a desktop with plenty of RAM will handle more than a phone.
▶Can I convert OFF back to 3DM?
Not here. We read 3DM and write OFF, but not the reverse. the universal 3D viewer
▶Which browsers does it work in?
Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, iOS and Android. No plugin and no extension.
Convert 3DM to something else
Save Rhino as an older version
Older software cannot open files saved by newer versions. These save a copy in the version the other side needs.
Convert something else to OFF
Or start from the universal 3D viewer.